Versatile Mig Welding - Weld With Gas

Really nice-looking welds are possible with oxyacetylene welding, though we have yet to see them materialize at the tips of our torches. Here is an example of the best we've been able to do so far. You can see the beginnings of the cool, stack-of-dimes look you want to achieve.

To see the difference, we fired up our MIG and TIG machines for a side-by-side comparison. The MIG welder is so easy to use, it's almost a no-brainer. We had to set the voltage and wire speed, but some machines can detect the thickness of the work and lock in the correct settings automatically. A MIG weld looks much more fluid and rope-like than a gas-welded joint. Some machines have a pulsed voltage supply that will give you the fish-scales look to your weld bead, but most welders designed for home use do not. Notice how each stop and start of the bead leaves a distinct (and some may say sloppy) break in the bead. That is characteristic of a MIG bead and can only be avoided by performing a continuous bead, something that may be difficult to do if you need to change hand or body positions as you travel along the joint. Also notice that the heat-affected zone, indicated by the color change around the bead, stays consistent along the joint. This is because MIG welding is also done very quickly and therefore doesn't allow much time to heat the metal up in the area surrounding the joint.

TIG welding, on the other hand, is a much slower and time-consuming process. Like with oxyacetylene welding, you have to manually add the filler material as you travel the length of the joint. TIG produces the neatest looking weld beads, giving you the traditional stack-of-dimes look. We obviously need more practice. Notice how the heat-affected zone is much wider at the end of the piece. As you reach the end of the joint, the heat has to spread out across a wider area because there is less distance to travel. This is why it is so easy to overheat and burn through the end of your joint.

You can also use an acetylene torch to remove a dent. High spots in a panel are areas where the metal has been stretched. Though it sounds counterintuitive, you can use heat to shrink metal. Use a welding tip the same size or smaller than the area you're working on. You'll also need a bucket of water, a rag, and a place to rest your torch. Heat the dent to cherry red.

As quickly as you can, hang the torch up and quench the area with the wet rag. This drastic drop in temperature causes the metal to shrink.

Use a hammer and dolly to smooth out the area. You may need to repeat the process a few times before the dent is completely straightened out.

Heat is also your friend when you encounter stuck fasteners. Exhaust bolts especially seem to become permanently fused after only a few days of driving. Don't reach for the hacksaw or cutoff wheel until you give this little trick a shot, though. Use your rosebud tip to heat the offending fasteners to a dull red color. Now touch a candle to the heated parts. The wax will melt and wick into the threads, making it a lot easier to remove.